1. Field of the Invention
The technical scope of the invention is that of firing safety devices for pyrotechnic devices.
2. Description of the Related Art
Safety devices (or SADs) are well known. They generally incorporate a barrier blocking a transmission channel which connects an igniter to a pyrotechnic charge.
The barrier thus positions itself in the way of the flame between the igniter and the charge thereby preventing the priming or firing of the latter.
Patents FR-2650662 and FR-2801099 thus disclose such known safety devices.
One of the problems encountered with these devices is their encumberment. The parts are relatively solid to ensure the interruption of the pyrotechnic train. The motor means enabling the barrier to be displaced must thus be powerful. More often than not, it is springs which are used, such springs remaining tensed during the storage phases possibly leading to a deterioration of their mechanical properties and a reduction in arming reliability.
Moreover, the springs do not enable an arming device with reversible function to be produced (that is to say, one which can move from its safety position to its armed position, and back again).
Small electric motors may be used, but these are cumbersome, fragile, difficult to integrate and require a substantial power source.
U.S. Pat. No. 3,750,589 discloses a safety and arming device which is activated by centrifugal force.
This device comprises several discs which are housed in a chamber that fills up with a fluid after firing. Each disc incorporates a channel, the centrifugal force causing the discs to be displaced with respect to one another in the fluid and the geometric characteristics of each disc are defined such that, after such a displacement, the different channels of each disc are aligned and form a continuous axial transmission channel between a primer and explosive charge.
The functioning of such a device is both complex and difficult to reproduce. Moreover, each disc constitutes in itself a barrier which must be displaced from a safety position in which it blocks the transmission channel to an armed position in which its hole is aligned with this channel.
Such a solution does not enable the dimensions and mass of the device to be reduced.